r sims are legal or illegal?

This is not the reason sim interposers may or may not be illegal in your country, since they dont actually use the emergency number, just abuse its extension in the imsi. The reason they may be illegal is the fact they change your phone imsi and tampering with that is illegal.

in most countries sim unlocking manually is not illegal but in case of jailbreak it void all warranty

SIM interposers that uses a national Emergency numbers (112, *77, etc) to initiate the MITM setup usually are illegal as most country's with a national emergency number have laws that prohibit the use of the number in any situation other than an actual emergency.

Note too that these interposer SIM cards are NOT actually unlocking your device, as without the interposer chip in place, the device goes right back to being locked to the carrier. They really are a hack, not a true unlocking procedure.